GASCO Exit Exam • Set 1 Question 13 of 30

What is 'rollover' in an LNG cargo tank?

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Direct Answer

Option B: Rapid mixing of two stratified liquid layers of different densities leading to sudden high gas evolution

Rollover occurs when stratified LNG layers equalize densities rapidly, releasing large volumes of boil-off gas and causing sharp tank pressure rise.

All Options

Over-rotation of the submerged pump impeller

Rapid mixing of two stratified liquid layers of different densities leading to sudden high gas evolution (Correct Answer)

Physical capsizing of the ship

Sloshing of cargo causing physical tank deformation

Detailed Explanation & Context

Rollover occurs when stratified LNG layers equalize densities rapidly, releasing large volumes of boil-off gas and causing sharp tank pressure rise.

Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • Advanced Training for Liquefied Gas Tanker Cargo Operations (GASCO).

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More Questions in GASCO Set 1

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Q1 What is the primary component of Liquefied Natural Gas (LNG)? Q2 At atmospheric pressure, what is the approximate boiling point of methane? Q3 Which code governs the construction and equipment of ships carrying liquefied gases in bulk? Q4 What is the function of Boil-Off Gas (BOG) on an LNG carrier? Q5 What gas is used to inert cargo tanks on gas carriers before introducing gas cargo? Q6 What is the Maximum Allowable Relief Valve Setting (MARVS) for a Type C independent tank on an LPG carrier? Q7 What risk is associated with rapid liquid cargo release onto steel deck structures? Q8 What type of pumps are most commonly used submerged inside LNG cargo tanks? Q9 What instrument measures low concentration flammable gas by catalytic oxidation? Q10 What safety feature automatically trips cargo valves and pumps during an emergency ESD activation?